Dual water supply system

ABSTRACT

A dual water supply system for allowing a water storage tank to be supplied with water harvested from a rainwater catchment area and from a mains supply of water is disclosed. The system includes a valve being coupled to a mains supply of water. The valve is responsive to the level of water within the tank to operate the valve if the level of water in the tank drops below a predetermined level and a pipe to introduce water from the mains supply through an opening into the tank whereby an outlet from the pipe is spaced from the top of the tank and is visible externally of the tank.

BACKGROUND OF THE INVENTION

This invention relates to sustainable water supply systems for urban buildings and is particularly concerned with water storage tanks for use in such systems.

The invention is an improvement of the systems disclosed in Australian patents 741136 and 750508.

DESCRIPTION OF THE PRIOR ART

In patent 750508, a water storage tank is disclosed which is connected to a town water supply and a domestic mains water supply. Valve means regulate the supply of town or mains water to the tank when the water level within the tank falls below a first pre-determined level and rises to a second pre-determined level. In this patent a dual float valve is located adjacent a lower portion of the tank and a float is used to regulate the introduction of town water into the tank dependent upon the level of the water within the tank. The introduction of town water into the tank occurs automatically and is not visible externally of the tank.

Patent 741136 discloses a complex arrangement with cables and floats for controlling a valve for introducing town water into a water storage tank. Once again, once town water is introduced into the tank, this introduction is not visible externally of the tank. The arrangement of patent 741136 is a mechanical one and is complex and relatively expensive.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a dual water supply system which at least minimises the disadvantages referred to above and which provides an alternative to the systems of the two earlier patents.

SUMMARY OF THE INVENTION

According to one aspect, the invention provides a dual water supply system for allowing a water storage tank to be supplied with water harvested from a rainwater catchment area and from a mains supply of water, the system including a valve being coupled to a mains supply of water, the valve being responsive to the level of water within the tank to operate the valve if the level of water in the tank drops below a predetermined level and a pipe to introduce water from the mains supply through an opening into the tank whereby an outlet from the pipe is spaced from the top of the tank and is visible externally of the tank.

In one embodiment, the pipe may be a stand pipe. In another embodiment, the pipe may extend in a generally horizontal direction.

The valve may be positioned within the tank. In this embodiment, the valve is suitably positioned above a level of an overflow outlet of the tank. In this manner, the valve is positioned above the maximum water level in the tank and in the air gap between the maximum water level and the top of the tank.

Alternately, the valve may be positioned externally to the tank. In this embodiment, the valve is suitably positioned above the tank. If the valve is external to the tank, it is suitably positioned within a housing.

The valve is preferably a float controllable valve having a float responsive to the level of water in the tank. The float may be connected to a float arm. The float may cause the float arm to move in response to changes in the water level. Alternatively, the float may move relative to the arm in response to changes in the water level.

The float controllable valve is preferably a sealed diaphragm type valve. If such a valve is positioned within the tank, it may be positioned either in an air gap above the maximum level of water within the tank or alternatively may be positioned below the maximum level of water within the tank and thereby be normally immersed in the water when the level of the water within the tank is at the maximum level.

The pipe is suitably in fluid communication with the valve. In one embodiment, the pipe projects from the valve. Where the pipe is a stand pipe, the stand pipe suitably extends generally upwardly from the valve.

The pipe outlet, as mentioned, extends above the upper level of the tank and as such there is a “visual air gap” between the outlet in the stand pipe and the top of the tank. This air gap ensures that there is no possibility of backflow of water from the tank into the mains supply coupled to the float controllable valve. Preferably, the stand pipe extends through a lid of the tank.

The present invention also extends to a tank provided with a dual water supply system in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference to the drawings in which:

FIG. 1 is a top view of a storage tank incorporating the dual water supply system according to an embodiment of the invention;

FIG. 2 is a diagrammatic vertical cross-sectional view of a storage tank incorporating the dual water supply system of an embodiment of the invention;

FIG. 3 is a detailed view of the float controllable valve and stand pipe employed in the dual water supply system of the invention; and

FIG. 4 is a diagrammatic vertical cross-sectional view of a storage tank incorporating the dual water supply system of another embodiment of the invention

DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 shows a plan view of a storage tank 10 having a dual water supply system of an embodiment of the invention. The lid 11 of the storage tank 10 has an opening in it relative to which is fitted a screen 12 which is adapted to filter vectors and myriad of various types of undesirable particles of rubbish from the water entering the storage tank. Rainwater harvested from a catchment area may be directed onto the screen 12 so that it may enter the tank. The screen is identified generally by the numeral 12. Typically, the screen has apertures of the order of 955 microns.

The tank 10 is provided with a vented vector proof overflow valve 13. The overflow valve 13 functions to ensure that when the tank is overfilled, excess water is allowed to drain from the tank 10.

As shown in FIG. 2, the tank 10 has various zones within it. These zones are identified by levels 1, 2, 3 and 4 within the tank. Level 4 denotes the maximum level to which water is normally contained within the tank. Should the flow of water from the catchment area be too great, excess water may exit through the valve 13 to ensure that the maximum level of water within the tank is maintained at level 4 to provide an air gap within the tank.

The volume of water between levels 3 and 4 within the tank is representative of rainwater stored within the tank 10. The volume of water between levels 2 and 3 is representative of water which may be introduced into the tank from a mains supply. Level 2 is representative of a minimum water quantity or level maintained within the tank 10 whilst level 1 denotes an anaerobic zone for water within the tank 10.

As shown in FIG. 2, water which exits through valve 13 may be directed to a storm water drain (not shown) by a dish 15 and pipe 14. Water may be drawn from the tank 10 via an outlet 16 coupled to a pump (not shown).

A supply 17 of mains water is coupled to a float controllable valve 18. The float controllable valve 18 shown in FIG. 2 is positioned within the air gap present in the tank 10 above level 4. If desired, the float controllable valve 18 may be located below level 4 and normally be immersed in water. The float controllable valve 18 is preferably a diaphragm valve such that when the valve 18 is immersed in water there is no danger of backflow of water from the tank to the mains supply.

As shown in FIG. 2, the float controllable valve 18 has a float 19 at the end of a float arm 20. The operation of the float control valve 18 is such that when the float 19 is in the dotted outline position at level 3, the float controllable valve 18 is off and the supply of mains water into the tank 10 is prevented. When the float 19 is in the full outline position at level 2, the float controllable valve 18 is open and mains water is introduced to the tank 10.

As shown in FIG. 2, a stand pipe 6 extends from the float controllable valve 18 and an outlet 21 from the stand pipe 6 is present above the outside of the tank lid 11 and is positioned to direct mains water on to the screen 12 from above the tank 10. In this way, the dual supply system of the invention provides a visual air gap between the lid of the tank 11 and the outlet 21. This ensures that there can be no possibility of the backflow of water from within the tank 10 into the mains supply and provides a visual assurance or indication that backflow prevention is provided by the system of the invention.

FIG. 3 shows the float controllable valve 18 and its relationship to the storage tank in greater detail. The float controllable valve 18 has a stand pipe 6 coupled to it which extends through a grommet 25 in the lid 11 of the tank. The outlet 21 of the stand pipe 6 is spaced from the tank lid 11 and the screen 12. A tank flange coupling 24 extends through a wall 22 of the tank and a supply of mains water maybe connected to the tank flange. Float 19 is coupled to the float controllable valve 18 by a rod or arm 20.

FIG. 4 shows a side diagrammatic view of another embodiment of the present invention. The embodiment of FIG. 4 has a number of similarities to the embodiment shown in FIGS. 1 to 3 and, for convenience like features will be designated by like reference numerals. These features need not be described further.

The embodiment of FIG. 4 differs form that of FIGS. 1 to 3 in that the valve 18′ is mounted within a housing 30 on top of the tank 10. Pipe 6′ extends generally horizontally from valve 18′ and has an outlet 21′ that allows water from the mains supply to enter the tank through screen 12′ in the opening in the top of the tank 10. The valve 18′ is controlled by a float 31 connected to a vertical float arm 32. Vertical float arm 32 may, for example, be a stainless steel rod.

The embodiment shown in FIG. 4 is especially suitable for installation in confined areas.

The system of the invention allows the storage tank to be topped up with water from a mains supply in a particularly simple manner whilst still ensuring that backflow of water into the mains supply is prevented and a visual indication or air gap is present to provide assurance of back flow prevention. In the preferred embodiments of the present invention shown in FIGS. 1 to 4, protection from backflow is provided in three ways:

-   -   1. the valve sits in the air gap in the tank or outside the         tank;     -   2. the valve, if submerged in water, does not allow tank water         to enter the inflow port because it is a diaphragm valve; and     -   3. the water enters the tank via a visual air gap.

Water drawn from the tank to outlet 15 occurs from just above the anaerobic zone. 

1. A dual water supply system for allowing a water storage tank to be supplied with water harvested from a rainwater catchment area and from a mains supply of water, the system including a valve being coupled to a mains supply of water, the valve being responsive to the level of water within the tank to operate the valve if the level of water in the tank drops below a predetermined level and a pipe to introduce water from the mains supply through an opening into the tank whereby an outlet from the pipe is spaced from the top of the tank and is visible externally of the tank.
 2. A dual water supply system as claimed in claim 1 wherein the pipe is a stand pipe.
 3. A dual water supply system as claimed in claim 1 the pipe extends in a generally horizontal direction.
 4. A dual water supply system as claimed in claim 1 wherein the valve is positioned within the tank.
 5. A dual water supply system as claimed in claim 4 wherein the valve is positioned above a level of an overflow outlet of the tank.
 6. A dual water supply system as claimed in claim 1 wherein the valve is positioned externally to the tank.
 7. A dual water supply system as claimed in claim 6 wherein the valve is positioned above the tank.
 8. A dual water supply system as claimed in claim 6 wherein the valve is positioned within a housing.
 9. A dual water supply system as claimed in claim 1 wherein the valve is a float controllable valve having a float responsive to the level of water in the tank.
 10. A dual water supply system as claimed in claim 9 wherein the float is connected to a float arm and the float causes the float arm to move in response to changes in the water level.
 11. A dual water supply system as claimed in claim 9 wherein the float is connected to a float arm and the float moves relative to the arm in response to changes in the water level.
 12. A dual water supply system as claimed in claim 1 wherein the valve is a sealed diaphragm type valve positioned either in an air gap above the maximum level of water within the tank or positioned below the maximum level of water within the tank and thereby normally immersed in the water when the level of the water within the tank is at the maximum level.
 13. A dual water supply system as claimed in claim 1 wherein the pipe is in fluid communication with the valve.
 14. A dual water supply system as claimed in claim 13 wherein the pipe projects from the valve.
 15. A dual water supply system as claimed in claim 14 wherein the pipe is a stand pipe that extends generally upwardly from the valve.
 16. A tank incorporating a dual water supply system as claimed in claim
 1. 